Embedded dielectric structures for active flow control plasma sources

ABSTRACT

An aircraft active flow control dielectric barrier discharge (DBD) device may include a machinable ceramic dielectric support having an aerodynamic surface shaped to form an exposed flush part of an airfoil surface on an aircraft. The DBD device may include at least two electrodes configured to be oppositely charged and spaced apart from each other on the dielectric support.

FIELD

The present application relates generally to improving flow controlacross aerodynamic surface of an aircraft. More specifically, thedisclosed embodiments relate to systems and methods for creating aplasma proximate an aerodynamic surface via an embedded dielectricstructure.

BACKGROUND

Performance of an aerodynamic structure on an aircraft is determined bythe interaction of the structures with the surrounding air as theaircraft flies. These interactions can lead to laminar flow of thepassing air, turbulent flow, or a combination of the two. Theinteractions may also be responsible for lift forces required for flightand drag forces.

Aerodynamic surfaces of aircraft are designed to manipulate and/orcontrol the interactions of the surfaces with the surrounding air. Forexample, the shape of an airplane wing is designed to make the speed ofairflow above the wing different from the speed of airflow below thewing, thereby creating lift. Some aerodynamic surfaces can change theirshape during flight by extending flaps, activating ailerons, movingrudders, or other such mechanical devices, thereby altering theinteraction of the surface with the passing air.

A non-mechanical method of altering airflow over an aerodynamic surfaceof an aircraft involves use of active flow control plasma sources, forexample dielectric barrier discharge (DBD) devices, to create a layer ofplasma proximate the aerodynamic surface as the aircraft flies. Thelayer of plasma typically has a lower pressure than the layer of passingair adjacent to the plasma. This lower pressure may draw the passing airtowards the aerodynamic surface more strongly than if the DBD devicewere omitted.

The utility of DBD devices has been shown in laboratory settings.However, the materials used in the laboratory do not lend themselves toimplementation on an aircraft. For example, many DBD devices areconstructed from various layers of flexible tape applied sequentially toan existing aerodynamic surface of a laboratory model. These tapestructures have three drawbacks. First, they are not robust and maybreak down prematurely in the presence of the plasma they create.Second, they are not scalable and would be difficult to apply to afull-size aircraft. Third, applying additional structure to an existingaircraft may adversely affect the aerodynamic properties of theaircraft.

SUMMARY

An aircraft active flow control dielectric barrier discharge (DBD)device may include a machinable ceramic dielectric support having anaerodynamic surface shaped to form an exposed flush part of an airfoilsurface on an aircraft. The DBD device may include at least twoelectrodes configured to be oppositely charged and spaced apart fromeach other on the dielectric support.

Another DBD device may include a rigid dielectric housing having anexterior aerodynamic surface shaped to form a portion of an airfoilstructure on an aircraft. The DBD device may include an exposedelectrode joined to the exterior aerodynamic surface of the housing anda buried electrode covered by the housing and spaced from the exposedelectrode. The DBD device may include a conductive interface structureconfigured to electrically connect the electrodes to a voltage sourceconfigured to apply a potential difference across the exposed electrodeand the buried electrode.

A method to improve aerodynamic properties of an aerodynamic surface mayinclude connecting a rigid DBD device to an airfoil structure. The DBDdevice may include a rigid dielectric carrier lying flush with anaerodynamic surface of the airfoil structure. The method may furtherinclude controlling air flow adjacent the aerodynamic surface of theairfoil structure by applying an alternating potential difference acrossan exposed electrode and a buried electrode. Applying the potentialdifference may thereby create a plasma proximate an upper surface of theDBD device.

The present disclosure provides various apparatuses and methods of usethereof. In some embodiments, an apparatus may include a rigiddielectric disposed within a recess in an aerodynamic structure and apair of electrodes disposed on opposite sides of the rigid dielectric.In some embodiments, a method may include connecting a rigid DBD deviceto an aerodynamic surface so that the dielectric lies flush with theaerodynamic surface.

Features, functions, and advantages may be achieved independently invarious embodiments of the present disclosure, or may be combined in yetother embodiments, further details of which can be seen with referenceto the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a dielectric barrier discharge(DBD) device embedded in an aerodynamic structure.

FIG. 2 is an exploded view of an embodiment of a DBD device and anaerodynamic structure, showing a recess in the structure configured toaccept the DBD device.

FIG. 3 is an unexploded view of the DBD device and aerodynamic structureof FIG. 2, showing the DBD device embedded within the structure.

FIG. 4 is a perspective view of an aircraft, showing prospectiveaerodynamic surfaces in which a DBD device may be embedded.

FIG. 5 is a perspective view of another aircraft, showing prospectiveaerodynamic surfaces in which a DBD device may be embedded.

FIG. 6 is a flow chart illustrating a method of improving aerodynamicproperties of an aerodynamic surface.

DESCRIPTION Overview

Various embodiments of a dielectric barrier discharge (DBD) devicehaving a rigid structure and configured to be embedded within anaerodynamic structure are described below and illustrated in theassociated drawings. Unless otherwise specified, the DBD device and/orits various components may, but are not required to, contain at leastone of the structure, components, functionality, and/or variationsdescribed, illustrated, and/or incorporated herein. Furthermore, thestructures, components, functionalities, and/or variations described,illustrated, and/or incorporated herein in connection with the presentteachings may, but are not required to, be included in other active flowcontrol plasma sources. The following description of various embodimentsis merely exemplary in nature and is in no way intended to limit thedisclosure, its application, or uses. Additionally, the advantagesprovided by the embodiments, as described below, are illustrative innature and not all embodiments provide the same advantages or the samedegree of advantages.

EXAMPLES, COMPONENTS, AND ALTERNATIVES

The following sections describe selected aspects of exemplary DBDdevices as well as related systems and/or methods. The examples in thesesections are intended for illustration and should not be interpreted aslimiting the entire scope of the present disclosure. Each section mayinclude one or more distinct inventions, and/or contextual or relatedinformation, function, and/or structure.

Example 1

This example describes an illustrative DBD device, as shown in FIG. 1.

FIG. 1 is a schematic sectional view of a DBD device, generallyindicated at 10, embedded in an aerodynamic or airfoil structure 12.Aerodynamic structure 12 may be a three-dimensional structure and mayextend in a direction perpendicular to the plane of FIG. 1. Examples ofaerodynamic structures include, but are not limited to, wings ofaircraft, helicopter blades or rotor blades, or other control surfacessuch as flaps, slats, ailerons, spoilers, winglets, landing gearsupports or others. DBD device 10 may include a dielectric 14, anexposed electrode 16, and a buried electrode 18.

Dielectric 14 may be any material having the appropriate electrical andmechanical properties for this use. Dielectric 14 may be made of amachinable ceramic material, for example, Macor™ machinableglass-ceramic and similar types of machinable ceramic material(s) and/oralumina and similar types of fine grained, polycrystallinemicrostructure machinable ceramics. Machinable ceramics may have theadvantage that they can be machined to generate any shape with relativeease. Dielectric 14 may act as a support for the exposed electrode andthe buried electrode. Machinable ceramics may also have a dielectricstrength similar to the flexible tape structures used in laboratoryexperiments on DBD devices.

Exposed electrode 16 may be any appropriate electrode or metallicmaterial. Exposed electrode 16 may be a part having a degree of rigiditybefore it is affixed to DBD device 10, such as a thin strip of metal.Alternately, the exposed electrode may be plasma sprayed, plated, orotherwise deposited directly onto dielectric 14. Such depositiontechniques may result in a thinner exposed electrode which may beadvantageous aerodynamically. Plasma spraying may be appropriate incases where dielectric 14 is a machinable ceramic, as ceramics cantolerate the high heat generated during such a deposition technique.Exposed dielectric 16 may be a refractory metal such as Molybdenum orTungsten or a more conventional metal such as copper, among others.

Buried electrode 18 may be any appropriate electrode or metallicmaterial. Since buried electrode 18 may be buried beneath dielectric 14within the aerodynamic structure 12, buried electrode 18 may notinteract with air passing over the aerodynamic structure. Thus, theremay be fewer constraints on the thickness of the buried electrode andthe materials used. Buried electrode 18 may be a part having a degree ofrigidity before it is affixed to DBD device 10, such as a thin strip ofmetal. Alternately, the buried electrode may be deposited ontodielectric 14.

In yet another alternative, buried electrode 18 may not be considered tobe a component of the DBD device and instead may be attached toaerodynamic structure 12. In this case, the buried electrode may makecontact with dielectric 14 once the DBD device is installed in theaerodynamic structure.

As stated above, the exposed electrode 16 and the buried electrode 18may be operatively coupled to dielectric 14. The two electrodes may beconfigured to be disposed on opposite sides of the dielectric. In thismanner, DBD device 10 may be similar to a capacitor in that it may havetwo conductors disposed on opposite sides of an insulator or dielectric.Dielectric 14 may be considered a housing that carries the twoelectrodes.

As in a standard capacitor, the two electrodes may be spaced from eachother in a vertical direction 20. The vertical distance between the twoelectrodes may be in a range of 1-5 mm, depending on the properties ofthe dielectric and a voltage applied. This vertical spacing may be thesame as the thickness of dielectric 14 in the vertical direction 20.Alternately, if one or both of the electrodes are disposed withindielectric 14, then the thickness of the dielectric may be greater thanthe vertical spacing between the two electrodes.

In contrast to a standard capacitor, the two electrodes may be spacedfrom each other in a horizontal direction. In relation to theaerodynamic structure 12, the buried electrode 18 may be spaced in adownwind or downstream direction 22 from the exposed electrode 16.Conversely, the exposed electrode 16 may be spaced in an upwind orupstream direction 24 from the buried electrode 18. The exposedelectrode and the buried electrode may overlap one another as viewedfrom above, or their edges may align in the vertical direction.

The two electrodes 16 and 18 may have a thickness in the verticaldirection in a range of approximately 0.1 to 1.0 mm, though other rangesarea also possible. In the horizontal direction, for example 22 or 24,the exposed electrode may have a width of approximately 5 mm, thoughother widths are also possible. The buried electrode may be four to fivetimes wider than the exposed electrode, though other widths are alsopossible.

DBD device 10 may be operatively coupled to a voltage source 26. Thevoltage source 26 may also be considered to be a power source for DBDdevice 10. Voltage source 26 may be configured to apply a potentialdifference across the exposed electrode and the buried electrode. Theapplied potential difference may be a direct current (DC) voltage, apulsed DC voltage, or an alternating current (AC) voltage. That is, therelative polarity of the two electrodes may be fixed or alternating. Ifthe applied voltage is not constant, it need not be strictly alternatingin a sinusoidal pattern. Non-constant voltages that have a sawtooth,triangular, or pulsed shape are also possible, among many others.Applying a potential difference across the two electrodes will producean electric field between and around the two electrodes.

A standard capacitor produces a substantially uniform electric field inthe region between the two conductors and a minimal “fringing” electricfield outside that region. In contrast, DBD device 10 may produce anon-uniform electric field in the region between the two conductors anda substantial fringing field outside of that region due to thehorizontal spacing between the two electrodes. As electric fields tendto be strongest proximate sharp edges of conductors, the electric fieldmay be strongest proximate a downstream edge 28 of the exposedelectrode.

As the airfoil structure 12 moves through the surrounding air, air mayflow over a surface 30 of the airfoil, the direction of airflowindicated by arrow 32. As this air passes though the strong electricfield proximate the downstream edge 28 of the exposed electrode 16, aportion of the passing air may be ionized and form a plasma 34. Plasma34 may be localized proximate an exterior surface 36 of dielectric 14and over buried electrode 18. Ceramic materials may have an advantage inbeing more able to withstand the presence of plasma 34 withoutdeteriorating than other dielectric structures.

Plasma 34 may have an effect on the air passing over the aerodynamicstructure 12. Plasma 34 may represent a region of lower air pressurethan the non-ionized air passing over airfoil 12. This may result in anupward force in direction 20 on the airfoil. That is, the presence ofplasma 34 on an upper surface of the airfoil may result in an additionallift force applied to the airfoil. Alternately, if the passing air isabout to separate from the surface 30 of airfoil 12 and create anaerodynamic stall, the lower pressure region of plasma 34 may apply adownward force to the passing air, thereby preventing or delaying thestall. This may allow airfoil 12 to move through the passing air at agreater angle of attack before inducing a stall.

DBD device 10 may be disposed within a recess 38 in aerodynamicstructure 12. The recess may be sized to receive the DBD device so thatthe exterior surface 36 of dielectric 14 forms an exposed flush part ofthe surface 30 of the airfoil. That is, the exterior surface of thedielectric may form a smooth continuation of the surface of the airfoil.If the exterior surface of the airfoil is generally flat, then theexterior surface of the dielectric may be flat as well, substantiallycontinuing the plane of the surface of the airfoil. If the surface ofthe airfoil is curved, the surface of the dielectric may be curved aswell, so that the exterior surfaces of the dielectric and the airfoiltogether form one continuous aerodynamic surface.

DBD device 10 disposed within recess 38 may be disposed proximate aleading edge 40 of the aerodynamic structure 12. The leading edge of theairfoil may be a portion of the airfoil disposed the farthest in theupwind direction 24. DBD device 10 may be disposed at other locations inairfoil 12 if active airflow control is desired at other locations.

DBD device 10 may include a conductive interface structure 42 configuredto electrically connect the electrodes to voltage source 26. Theconductive interface structure may be any appropriate structureconfigured to mate with a corresponding structure on the airfoil so asto establish electrical connection between the voltage source 26 and theelectrodes 16 and 18. For example, conductive interface structure 42 mayinclude one or more plug structures 44 configured for connection to thevoltage source 26. Connecting wires 46 may be included in airfoil 12configured to connect the DBD device to the voltage or power source.

DBD device 10 may include a controller 48. Controller 48 may beprogrammed to alter the power supplied from the voltage source to theelectrodes. Controller 48 may alter the amount of power supplied, aswell as the various characteristics of the potential difference appliedacross the electrodes, such as the amplitude, frequency, and waveform ofthe applied voltage. Controller 48 may operate at the direction of auser, such as a pilot, or autonomously. For example, controller 48 maybe programmed to activate DBD device 10 during takeoff, landing, if apredetermined speed threshold is crossed, if a predetermined angle ofattack for the airfoil is exceeded, or any other criteria crosses acritical value.

An alternative embodiment of DBD device 10 may have the exposedelectrode partially embedded within dielectric 14, for example atlocation 50 indicated in dashed lines. In this alternative, the exposedelectrode may lie flush with the aerodynamic surface 30 of aerodynamicstructure 12. Thus, the exposed electrode, a portion of the exteriorsurface 36 of the dielectric and the aerodynamic surface 30 may togetherform a continuous aerodynamic surface. This alternative embodiment maythen have no effect on the aerodynamic properties of the aerodynamicstructure when the DBD device is in an unactivated state.

Still another alternative embodiment of DBD device 10 may have theexposed electrode in a hybrid or angled position where an upstream edge52 of the exposed dielectric 14 lies embedded in dielectric 14 and flushwith the surface of the aerodynamic structure while the downstream edge28 of the exposed electrode lies above the exterior surface 36 of thedielectric 14.

Example 2

This example describes an illustrative embodiment of a DBD device whichmay serve as a plasma source for active airflow control, as shown inFIGS. 2 and 3.

FIG. 2 is an exploded view of an embodiment of an exemplary DBD device,generally indicated at 100, and an aerodynamic structure 102, showing arecess 104 in the structure configured to accept the DBD device.

Aerodynamic structure 102 is shown in FIG. 2 having the shape of anairfoil. During flight operation, air may move across the aerodynamicstructure generally in a direction indicated by arrow 106. Recess 104may be located proximate a leading edge 108 of airfoil 102. Recess 104may be sized and configured to accept the component pieces of DBD device100.

DBD device 100 may include a rigid dielectric housing 110, an exposedelectrode 112, and a buried electrode 114. DBD device 100 may beconfigured to be attached to airfoil structure 102 by any appropriatemechanism. It may be advantageous to operatively couple DBD device 100to the airfoil in such a manner that the DBD device may be removedrelatively easily and replaced. For example, DBD device 100 may beattached via one or more bolts 116, though other attachment mechanismswould also be possible, such as via screws, rivets, pins, or by simplysnapping in place among others.

Rigid dielectric housing 110 may comprise a ceramic material. Forexample, housing 110 may be a machinable ceramic material such as Macor™machinable glass-ceramic, alumina, or other types of fine grained,polycrystalline microstructure machinable ceramics. The exposed andburied electrodes may be mounted or otherwise operatively coupled tohousing 110. The DBD device may be placed as a whole into recess 104 andreversibly drawn out for purposes of replacing the device should one ofthe components deteriorate.

Exposed electrode 112 may be joined to an exterior aerodynamic surface118 of housing 110. The exposed electrode may be a semi-rigid membercapable of maintaining a shape when not attached to housing 110 asdepicted in FIG. 2. Alternately, exposed electrode 112 may be depositedon housing 110 via a deposition technique familiar to a person skilledin the art.

Buried electrode 114 may be any appropriate conductor and may be coveredby the housing when DBD device 100 is disposed within recess 104. Theburied electrode may be spaced from the exposed electrode in a verticaldirection away from aerodynamic surface 118 and in a downwind direction106. Buried electrode 114 may alternately be embedded in housing 110.

As with DBD device 10, DBD device 100 may include a conductive interfacestructure configured to electrically connect the electrodes to a voltagesource configured to apply a potential difference across the exposedelectrodes and the buried electrode. The interface may include a plugstructure configured for connection to an AC power source. DBD device100 may include a controller programmed to alter power supplied from thevoltage source to the electrodes.

FIG. 3 is an unexploded view of DBD device 100 and aerodynamic structure102, showing the DBD device embedded within the recess in the structure.The exterior aerodynamic surface 118 of housing 110 may be shaped toform a portion of airfoil structure 102. That is, the exposed surface118 of the dielectric may form a smooth continuation of an aerodynamicsurface 120 of the aerodynamic structure 102. Thus configured, the DBDdevice 100 may have a minimal impact on the flow of air over theaerodynamic structure when DBD device 100 is not in an activated state.Exposed electrode 112 may be thin, for example in a range of 0.1 to 1.0mm. Such a thin exposed electrode may have minimal effect on the passingair when the DBD device is in an unactivated state.

Example 3

This example describes possible installation locations for DBD deviceson various exemplary aircraft, as shown in FIGS. 4 and 5.

FIG. 4 is a perspective view of an exemplary aircraft, specifically ahelicopter, generally indicated at 200. Aircraft 200 may includeaerodynamic structures such as, one or more main rotor blades 202, oneor more tail rotor blades 204, a tail fin 206, or one or more wings 208,among others. Airflow over any one of these aerodynamic structures maybe improved by an addition of an active airflow control device, such asDBD devices 10 or 100.

A DBD device may, for example, be embedded within a main rotor blade 202proximate a leading edge 210 of the rotor blade. A DBD device such as 10or 100 may have a length that is customized to fit the length of theaerodynamic structure in which the device may be embedded. For example,a single long DBD device may be disposed within the rotor blade 202along most of the length of the blade. Alternately, DBD devices may havea shorter length, for example approximately 0.5 meters. Such a shorterDBD device may be installed proximate the leading edge 210 and a tip 212of the rotor blade where the speed of the blades will be greatest. Inyet another alternative, a plurality of DBD devices may be disposed insuccession along the length of a rotor blade, thereby spanning most ofthe length of the blade with multiple shorter DBD devices. One or moreDBD devices, of similar or varying lengths, may be disposed proximateaerodynamic surfaces of any of the relevant aerodynamic structures ofhelicopter 200. Depending on the aerodynamic properties of the relevantsurfaces, it may or may not be advantageous to dispose a DBD deviceproximate a leading edge of the surface.

FIG. 5 is a perspective view of another exemplary aircraft, specificallyan airplane, generally indicated at 300. Aircraft 300 may includeaerodynamic structures such as one or more wings 302, a verticalstabilizer or tail fin 304, one or more horizontal stabilizers 306, afuselage 308, an engine cowling, and various landing gear structures,among others. Any one of these structures may have improved airflowcharacteristics with the addition of one or more DBD devices, such asDBD devices 10 or 100.

As with the leading edge of rotor blade 202 on helicopter 200, one longor many short DBD devices may be embedded within wing 302 proximate aleading edge 310 of the wing. Alternately, one or more DBD devices maybe embedded within wing 302 proximate one or more flaps 312. DBD devicesmay be disposed proximate leading edges of stabilizers 304 and 306, andproximate a leading edge 314 of fuselage 308, that is, proximate a noseof the aircraft.

In some embodiments, a DBD device may have a length of approximately 2meters. DBD devices may require power in a range of 2-5 watts per linearfoot, though other ranges are also possible. It may be advantageous toemploy shorter DBD devices as they may be more modular and any singledevice may be configured to be embedded within more than one of theaerodynamic structures on an aircraft.

Example 4

This example describes an illustrative method for improving aerodynamicproperties of an aerodynamic surface, which may be used in conjunctionwith any of the apparatuses described herein, as shown in FIG. 6.

FIG. 6 depicts multiple steps of a method, generally indicated at 400,for improving aerodynamic properties of an aerodynamic surface. Method400 may be used in conjunction with any of the DBD devices depicted inand described in reference to FIGS. 1-5. Although various steps ofmethod 400 are described below and depicted in FIG. 6, the steps neednot necessarily all be performed, and in some cases may be performed ina different order than the order shown.

Method 400 may include a step 402 of connecting a rigid dielectricbarrier discharge (DBD) device to an airfoil structure. The DBD devicemay include a rigid dielectric carrier lying flush with an aerodynamicsurface of the airfoil structure. Connecting the DBD device to theairfoil structure may include securing the DBD device within a recess inthe airfoil structure. The DBD device may be secured via bolts, screws,rivets, plug structures, or any other appropriate attachment devices.The DBD device may be provided in the form of a cartridge configured toplug into the airfoil structure.

The DBD device may include a rigid dielectric carrier. For example, thedielectric 14 of DBD device 10 or the housing 110 of DBD device 100 maybe considered a rigid dielectric carrier. Upon being connected to theairfoil structure, the rigid dielectric carrier may lie flush with anaerodynamic surface of the airfoil structure. When lying flush, anexposed surface of the rigid dielectric carrier may smoothly continue aportion of the aerodynamic surface which lies proximate the exposedsurface of the carrier.

Method 400 may include a step 404 of controlling air flow adjacent anaerodynamic surface of the airfoil structure by applying an alternatingpotential difference across an exposed electrode and a buried electrode.The exposed electrode and the buried electrode may be spaced from oneanother across the rigid dielectric carrier. The exposed electrode maybe disposed on the exposed surface of the carrier and the buriedelectrode may be buried beneath the carrier within the airfoilstructure. The buried electrode may be disposed downwind of the exposedelectrode.

The alternating potential difference applied across the electrodes mayhave a sinusoidally oscillating amplitude. Alternately, other waveformssuch as triangular waves, sawtooth waves, or trains of pulses are alsopossible. The potential difference may be applied across the electrodesby connecting a voltage source to the electrodes via a conductiveinterface structure. This connection may be made at substantially thesame time as the time when the DBD device is connected to the airfoilstructure.

Applying the alternating potential difference to the electrodes maythereby create a plasma proximate an upper surface of the dielectricbarrier discharge device. The plasma may be created as described inreference to DBD device 10 and FIG. 1. The upper surface of the DBDdevice which is proximate the plasma may be the exposed surface of therigid dielectric carrier included in the DBD device. The plasma may bedisposed over the buried electrode.

Method 400 may include an optional step 406 of unplugging and replacingthe DBD device. Components of the DBD device may deteriorate with time,exposure to outside elements, and even exposure to the plasma created bythe DBD device itself. It may be preferable to form the rigid dielectriccarrier from a machinable ceramic in order to better withstand exposureto the plasma. In Example 2 describing DBD device 100 unplugging andreplacing the DBD device may be as simple as removing a pair of bolts,removing the DBD device, plugging a new device in, and securing the newdevice with a pair of bolts. A technician could likely accomplish such atask in a few minutes.

Method 400 may include an optional step 408 of altering the potentialdifference applied across the electrodes. The potential difference maybe altered by a user such as a pilot. Alternately or additionally, thepotential difference may be altered at the direction of a controllerdevice. The potential difference may be altered at a time chosen by auser or may be altered automatically when a predetermined criteria ismet. For example, the potential difference may be altered, at leastpartially, based on an air speed of the aircraft. In another example,the potential difference may be altered, at least partially, based on anangle of attack of the airfoil structure. Improving the aerodynamicproperties of the aerodynamic surface may be important when the aircrafthas reached a certain speed or when the angle of attack of the airfoilstructure has reached a certain value.

Example 5

This section describes additional aspects and features of embodiments,presented without limitation as a series of paragraphs, some or all ofwhich may be alphanumerically designated for clarity and efficiency.Each of these paragraphs can be combined with one or more otherparagraphs, and/or with disclosure from elsewhere in this application inany suitable manner. Some of the paragraphs below expressly refer to andfurther limit other paragraphs, providing without limitation examples ofsome of the suitable combinations.

A1. An aircraft active flow control dielectric barrier discharge device,comprising:

a machinable ceramic dielectric support having an aerodynamic surfaceshaped to form an exposed flush part of an airfoil surface on anaircraft; and

at least two electrodes configured to be oppositely charged and spacedapart from each other on the dielectric support.

A2. The aircraft active flow control dielectric barrier discharge deviceof claim A1, wherein the device is proximate a leading edge of theairfoil surface.

A3. The aircraft active flow control dielectric barrier discharge deviceof claim A1, wherein the at least two electrodes are configured toaccept an alternating potential difference.

A4. The aircraft active flow control dielectric barrier discharge deviceof claim A1, wherein a first electrode of the at least two electrodes isdisposed on the aerodynamic surface of the dielectric support, and asecond electrode of the at least two electrodes is buried beneath thedielectric support.

A5. The aircraft active flow control dielectric barrier discharge deviceof claim A4, wherein the second electrode is disposed downwind of thefirst electrode.

A6. The aircraft active flow control dielectric barrier discharge deviceof claim A5, wherein the second electrode has a width of at least twicea width of the first electrode, as measured in the downwind direction.

A7. The aircraft active flow control dielectric barrier discharge deviceof claim A1, further comprising a conductive interface structureconfigured to electrically connect the at least two electrodes to avoltage source configured to apply a potential difference across two ofthe at least two electrodes.

A8. The aircraft active flow control dielectric barrier discharge deviceof claim A7, wherein the conductive interface structure includes a plugstructure configured for connection to an AC power source.

A9. The aircraft active flow control dielectric barrier discharge deviceof claim A8, further comprising a controller programmed to alter powersupplied from the source to the electrodes based on an aircraft speedthreshold.

A10. The aircraft active flow control dielectric barrier dischargedevice of claim A1, further comprising a controller programmed to alterpower supplied from the source to the electrodes based on an angle ofattack trajectory threshold.

A11. The aircraft active flow control dielectric barrier dischargedevice of claim A1, wherein the aerodynamic surface forms an externalsurface of an aircraft wing.

A12. The aircraft active flow control dielectric barrier dischargedevice of claim A1, wherein the aerodynamic surface forms an externalsurface of an aircraft tail fin.

A13. The aircraft active flow control dielectric barrier dischargedevice of claim A1, wherein the aerodynamic surface forms an externalsurface of an aircraft nose.

A14. The aircraft active flow control dielectric barrier dischargedevice of claim A1, wherein the aerodynamic surface forms an externalsurface of an aircraft rotor blade.

B1. A dielectric barrier discharge device, comprising:

a rigid dielectric housing having an exterior aerodynamic surface shapedto form a portion of an airfoil structure on an aircraft;

an exposed electrode joined to the exterior aerodynamic surface of thehousing;

a buried electrode covered by the housing, spaced from the exposedelectrode; and

a conductive interface structure configured to electrically connect theelectrodes to a voltage source configured to apply a potentialdifference across the exposed electrode and the buried electrode.

B2. The dielectric barrier discharge device of claim B1, wherein thedielectric housing comprises a ceramic material.

B3. The dielectric barrier discharge device of claim B1, wherein theburied electrode is embedded in the housing.

B4. The dielectric barrier discharge device of claim B1, wherein theconductive interface structure includes a plug structure configured forconnection to an AC power source.

B5. The dielectric barrier discharge device of claim B1, furthercomprising a controller programmed to alter voltage supplied from thesource to the electrodes.

C1. A method to improve aerodynamic properties of an aerodynamicsurface, the method comprising:

connecting a rigid dielectric barrier discharge device to an airfoilstructure, the dielectric barrier discharge device including a rigiddielectric carrier lying flush with an aerodynamic surface of theairfoil structure; and

controlling air flow adjacent the aerodynamic surface of the airfoilstructure by applying an alternating potential difference across anexposed electrode and a buried electrode, thereby creating a plasmaproximate an upper surface of the dielectric barrier discharge device.

C2. The method of claim C1, wherein the buried electrode is disposeddownwind of the exposed electrode.

C3. The method of claim C1, wherein the plasma is created over theburied electrode.

C4. The method of claim C1, wherein the applying step includeselectrically connecting a voltage source to the electrodes via aconductive interface structure.

C5. The method of claim C1, further comprising unplugging and replacingthe dielectric barrier discharge device.

C6. The method of claim C1, wherein the dielectric barrier dischargedevice is provided in the form of a cartridge configured to plug intothe airfoil structure.

C7. The method of claim C1, further comprising altering the potentialdifference at least partially based on air speed.

C8. The method of claim C1, further comprising altering the potentialdifference at least partially based on an angle of attack of the airfoilstructure.

ADVANTAGES, FEATURES, BENEFITS

The different embodiments of the dielectric barrier discharge devices(DBD) described herein provide several advantages over known solutionsfor providing air flow control using plasma sources. For example, theillustrative embodiments of DBD devices described herein allow the DBDdevice to be embedded within an aerodynamic structure. Additionally, andamong other benefits, illustrative embodiments of the DBD devicesdescribed herein allow the DBD devices to be formed into an easilyreplaceable part. No known system or device can perform these functions,particularly outside of a laboratory setting. Thus, the illustrativeembodiments described herein are particularly useful for providingactive air flow control for in service aircraft. However, not allembodiments described herein provide the same advantages or the samedegree of advantage.

CONCLUSION

The disclosure set forth above may encompass multiple distinctinventions with independent utility. Although each of these inventionshas been disclosed in its preferred form(s), the specific embodimentsthereof as disclosed and illustrated herein are not to be considered ina limiting sense, because numerous variations are possible. To theextent that section headings are used within this disclosure, suchheadings are for organizational purposes only, and do not constitute acharacterization of any claimed invention. The subject matter of theinvention(s) includes all novel and nonobvious combinations andsubcombinations of the various elements, features, functions, and/orproperties disclosed herein. The following claims particularly point outcertain combinations and subcombinations regarded as novel andnonobvious. Invention(s) embodied in other combinations andsubcombinations of features, functions, elements, and/or properties maybe claimed in applications claiming priority from this or a relatedapplication. Such claims, whether directed to a different invention orto the same invention, and whether broader, narrower, equal, ordifferent in scope to the original claims, also are regarded as includedwithin the subject matter of the invention(s) of the present disclosure.

I claim:
 1. An aircraft active flow control dielectric barrier dischargedevice, comprising: a machinable ceramic dielectric support having anaerodynamic surface shaped to form an exposed flush part of an airfoilsurface on an aircraft; and at least two electrodes configured to beoppositely charged and spaced apart from each other on the dielectricsupport.
 2. The aircraft active flow control dielectric barrierdischarge device of claim 1, wherein the device is proximate a leadingedge of the airfoil surface.
 3. The aircraft active flow controldielectric barrier discharge device of claim 1, wherein a firstelectrode of the at least two electrodes is disposed on the aerodynamicsurface of the dielectric support, and a second electrode of the atleast two electrodes is buried beneath the dielectric support.
 4. Theaircraft active flow control dielectric barrier discharge device ofclaim 3, wherein the second electrode is disposed downwind of the firstelectrode.
 5. The aircraft active flow control dielectric barrierdischarge device of claim 4, wherein the second electrode has a width ofat least twice a width of the first electrode, as measured in thedownwind direction.
 6. The aircraft active flow control dielectricbarrier discharge device of claim 1, further comprising a conductiveinterface structure configured to electrically connect the at least twoelectrodes to a voltage source configured to apply a potentialdifference across two of the at least two electrodes.
 7. The aircraftactive flow control dielectric barrier discharge device of claim 6,wherein the conductive interface structure includes a plug structureconfigured for connection to an AC power source.
 8. The aircraft activeflow control dielectric barrier discharge device of claim 7, furthercomprising: a controller programmed to alter power supplied from the ACpower source to the electrodes based at least partially on an aircraftspeed.
 9. The aircraft active flow control dielectric barrier dischargedevice of claim 7, further comprising: a controller programmed to alterpower supplied from the AC power source to the electrodes based at leastpartially on an angle of attack trajectory.
 10. The aircraft active flowcontrol dielectric barrier discharge device of claim 1, wherein theaerodynamic surface forms an external surface of at least an aircraftwing, an aircraft nose, and an aircraft rotor blade.
 11. A dielectricbarrier discharge device, comprising: a rigid dielectric housing havingan exterior aerodynamic surface shaped to form a portion of an airfoilstructure on an aircraft; an exposed electrode joined to the exterioraerodynamic surface of the housing; a buried electrode covered by thehousing, spaced from the exposed electrode; and a conductive interfacestructure configured to electrically connect the electrodes to a voltagesource configured to apply a potential difference across the exposedelectrode and the buried electrode.
 12. The dielectric barrier dischargedevice of claim 11, wherein the dielectric housing comprises a ceramicmaterial.
 13. The dielectric barrier discharge device of claim 11,wherein the buried electrode is embedded in the housing.
 14. Thedielectric barrier discharge device of claim 11, further comprising: apower source connected to the conductive interface structure, and acontroller programmed to alter power supplied from the source to theelectrodes at least partially based on air speed or angle of attack. 15.A method to improve aerodynamic properties of an aerodynamic surface,the method comprising: connecting a rigid dielectric barrier dischargedevice to an airfoil structure, the dielectric barrier discharge deviceincluding a rigid dielectric carrier lying flush with an aerodynamicsurface of the airfoil structure; and controlling air flow adjacent theaerodynamic surface of the airfoil structure by applying an alternatingpotential difference across an exposed electrode and a buried electrode,thereby creating a plasma proximate an upper surface of the dielectricbarrier discharge device.
 16. The method of claim 15, wherein the buriedelectrode is disposed downwind of the exposed electrode.
 17. The methodof claim 15, wherein the plasma is created over the buried electrode.18. The method of claim 15, further comprising: unplugging and replacingthe dielectric barrier discharge device.
 19. The method of claim 15,wherein the dielectric barrier discharge device is provided in the formof a cartridge configured to plug into the airfoil structure.
 20. Themethod of claim 15, further comprising: altering the potentialdifference at least partially based on air speed or an angle of attackof the airfoil structure.